From 83f48dd175baf208e62f38197efdbe1a521bd96c Mon Sep 17 00:00:00 2001
From: kolaente <k@knt.li>
Date: Mon, 1 Feb 2021 21:05:53 +0100
Subject: [PATCH] Increase and decrease the list metrics counter with events

---
 pkg/metrics/metrics.go  |  2 +-
 pkg/models/events.go    |  9 +++++++++
 pkg/models/list.go      | 18 +++++++++++++-----
 pkg/models/listeners.go | 30 ++++++++++++++++++++++++++++++
 4 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/pkg/metrics/metrics.go b/pkg/metrics/metrics.go
index da5240182..fe40a9d29 100644
--- a/pkg/metrics/metrics.go
+++ b/pkg/metrics/metrics.go
@@ -155,7 +155,7 @@ func UpdateCount(update int64, key string) {
 		}
 	}
 	if update < 0 {
-		err := keyvalue.DecrBy(key, update)
+		err := keyvalue.DecrBy(key, update*-1)
 		if err != nil {
 			log.Error(err.Error())
 		}
diff --git a/pkg/models/events.go b/pkg/models/events.go
index fb225b837..bd0128992 100644
--- a/pkg/models/events.go
+++ b/pkg/models/events.go
@@ -106,6 +106,15 @@ func (l *ListUpdatedEvent) TopicName() string {
 	return "list.updated"
 }
 
+type ListDeletedEvent struct {
+	List *List
+	Doer *user.User
+}
+
+func (t *ListDeletedEvent) TopicName() string {
+	return "list.deleted"
+}
+
 ////////////////////
 // Sharing Events //
 ////////////////////
diff --git a/pkg/models/list.go b/pkg/models/list.go
index b9cb17244..c08d1922c 100644
--- a/pkg/models/list.go
+++ b/pkg/models/list.go
@@ -25,7 +25,6 @@ import (
 	"code.vikunja.io/api/pkg/log"
 
 	"code.vikunja.io/api/pkg/files"
-	"code.vikunja.io/api/pkg/metrics"
 	"code.vikunja.io/api/pkg/user"
 	"code.vikunja.io/web"
 	"xorm.io/builder"
@@ -493,7 +492,6 @@ func CreateOrUpdateList(s *xorm.Session, list *List, auth web.Auth) (err error)
 
 	if list.ID == 0 {
 		_, err = s.Insert(list)
-		metrics.UpdateCount(1, metrics.ListCountKey)
 	} else {
 		// We need to specify the cols we want to update here to be able to un-archive lists
 		colsToUpdate := []string{
@@ -643,11 +641,21 @@ func (l *List) Delete(s *xorm.Session, a web.Auth) (err error) {
 	if err != nil {
 		return
 	}
-	metrics.UpdateCount(-1, metrics.ListCountKey)
 
-	// Delete all todotasks on that list
+	// Delete all tasks on that list
 	_, err = s.Where("list_id = ?", l.ID).Delete(&Task{})
-	return
+	if err != nil {
+		return
+	}
+
+	doer, err := user.GetFromAuth(a)
+	if err != nil {
+		return err
+	}
+	return events.Publish(&ListDeletedEvent{
+		List: l,
+		Doer: doer,
+	})
 }
 
 // SetListBackground sets a background file as list background in the db
diff --git a/pkg/models/listeners.go b/pkg/models/listeners.go
index fce83ad3e..b158efd75 100644
--- a/pkg/models/listeners.go
+++ b/pkg/models/listeners.go
@@ -17,6 +17,7 @@
 package models
 
 import (
+	"code.vikunja.io/api/pkg/metrics"
 	"encoding/json"
 
 	"code.vikunja.io/api/pkg/events"
@@ -25,6 +26,8 @@ import (
 
 func RegisterListeners() {
 	events.RegisterListener((&TaskCreatedEvent{}).TopicName(), &SendTaskCreatedNotification{})
+	events.RegisterListener((&ListCreatedEvent{}).TopicName(), &IncreaseListCounter{})
+	events.RegisterListener((&ListDeletedEvent{}).TopicName(), &DecreaseListCounter{})
 }
 
 type SendTaskCreatedNotification struct {
@@ -43,3 +46,30 @@ func (s *SendTaskCreatedNotification) Handle(payload message.Payload) (err error
 
 	return nil
 }
+
+///////
+// List Event Listeners
+
+type IncreaseListCounter struct {
+}
+
+func (s *IncreaseListCounter) Name() string {
+	return "increase.list.counter"
+}
+
+func (s *IncreaseListCounter) Handle(payload message.Payload) (err error) {
+	metrics.UpdateCount(1, metrics.ListCountKey)
+	return nil
+}
+
+type DecreaseListCounter struct {
+}
+
+func (s *DecreaseListCounter) Name() string {
+	return "decrease.list.counter"
+}
+
+func (s *DecreaseListCounter) Handle(payload message.Payload) (err error) {
+	metrics.UpdateCount(-1, metrics.ListCountKey)
+	return nil
+}